A display element provided with a current-driven light-emitting unit, and a display device provided with the display element, are well known. For example, a display element provided with a light-emitting unit that uses electroluminescence of an organic material (hereinafter, may be merely referred to as “organic EL display element”) attracts attention as a display element that is capable of high-luminance light emission by low-voltage DC driving.
As with liquid crystal display devices, in the field of, for example, display devices, each of which is provided with an organic EL display element, as well, a simple matrix method and an active matrix method are well known as driving methods. The active matrix method has a disadvantage that a structure becomes complicated. However, the active matrix method has, for example, an advantage that the brightness of an image can be made high. An organic EL display element driven by the active matrix method is provided with not only a light-emitting unit that includes an organic layer including a light-emitting layer and the like, but also a driving circuit having a driving transistor for driving the light-emitting unit.
A value of a current flowing through the driving transistor is influenced not only by a voltage of a gate electrode with respect to a source region of the driving transistor (so-called a voltage between the gate and the source) but also by a threshold voltage of the driving transistor. The threshold voltage of the driving transistor disperses on a display element basis, and therefore causes uneven brightness. For example, Japanese Patent Application Laid-Open No. 2008-287139 (Patent Document 1) discloses the feature of performing the operation of canceling an influence, which is exerted by the dispersion in threshold voltage of a driving transistor, every time a video signal is written to a display element.